TRANSLATIONAL REGULATION OF TRA-2 BY ITS 3' UNTRANSLATED REGION CONTROLS SEXUAL IDENTITY IN C-ELEGANS

C. elegans hermaphrodites make sperm and then oocytes in an otherwise female animal. Gain-of-function mutations in the sex-determining gene tra-2 (tra-2(gf)) transform hermaphrodites into females (spermless her maphrodites). The tra-2(gf) mutations map to a perfect direct repeat i n the 3' untranslated region; each repeat is called a direct repeat el ement (DRE). Three experiments demonstrate that DREs repress tra-2 at the translational level. First, tra-2(gf) mRNAs are associated with la rger polysomes than are their wild-type counterparts. Second, translat ion of a reporter RNA is inhibited by DREs. Third, disruption of DREs does not increase tra-2 mRNA levels. An RNA binding activity specifica lly associates with the DREs. We propose that tra-2 translation is inh ibited by association of an RNA binding-factor with the DREs and that this translational control is essential for development of C. elegans as a hermaphrodite/male species.